Heat exchanger

Abstract

A heat exchanger includes a pair of header pipes, tubes disposed between the header pipes, and radiation fins provided along the tubes. Each of the header pipes has a plurality of connection holes for the tubes. Each of the header pipes is formed by bending a longitudinal flat plate in the form of a pipe and connecting the side edge portions of the bent plate to each other. The side edge portions of the bent longitudinal plate have connecting portions which are connected to each other with a junction area larger than the cross-sectional area defined by the thickness and length of each header pipe at a position other than the side edge portions. The connection holes are processed before the longitudinal flat plate is bent, and therefore, can be easily and precisely formed at desired positions. The manufacture of the heat exchanger can be simplified and the cost for the manufacture can be reduced. The connection strength of the side edge portions can be increased by the larger connection area of the connecting portions. The strength of the header pipe can be maintained over a long period of time.

What is claimed is: 
     
       1. A heat exchanger comprising: a pair of tubular header pipes having axes which are parallel, each said header pipe having a plurality of axially spaced oblong slots;   a plurality of generally flat tubes extending between said header pipes and individually through said slots, for providing fluid communication between said header pipes;   a plurality of radiation fins extending between adjacent flat tubes; and   wherein said header pipes each comprise a single bent rectangular plate member having a plurality of oblong slots, and two side edge connecting portions, wherein one side edge connecting portion comprises an outwardly projecting U-shaped flange portion, and the other side edge connecting portion comprises an outwardly extending flange portion, said flat tubes being received within said slots, wherein said slots of said single bent rectangular plate member are sized to engage and press into said flat tubes to fixedly hold said flat tubes in place, and wherein said U-shaped flange portion of said single bent rectangular plate member extends over and retains the outwardly extending flange portion so that the single bent rectangular plate member forms a tubular header pipe.   
     
     
       2. The heat exchanger according to claim 1 wherein said heat exchanger is brazed to retain said extending folded portion over said other side edge portion. 
     
     
       3. A heat exchanger including at least one tubular header pipe formed from a rectangular plate having a pair of parallel opposed side edge portions which are joined together and at least one slot with sides for attachment of a heat exchange tube, at least one heat exchange tube being connected with said header pipe in fluid communication for effecting the flow of a heat exchange medium through said heat exchanger, and a plurality of fin units provided along the outside of said heat exchange tube, the improvement comprising said rectangular plate comprising a single bent rectangular plate including one opposed side edge portion having an extended folded portion which interlocks with and retains the other opposed side edge portion to form said tubular header pipe, wherein said slot of said bent rectangular plate is shaped and sized to engage and press into said heat exchange tube to hold it in place. 
     
     
       4. A heat exchanger according to claim 3 wherein said one opposed side edge portion includes an outwardly projecting U-shaped flange and the other side edge portion includes a radially outwardly extending flange, said U-shaped flange receiving said radially outwardly extending flange to form an interlocked seam of said header pipe. 
     
     
       5. A heat exchanger according to claim 3 wherein said header pipe includes at least one oblong slot for reception of said heat exchange tube. 
     
     
       6. A heat exchanger according to claim 3 wherein said heat exchanger is brazed to retain said opposed side edge portions in said interlocked position.